This invention relates generally to high resolution amplitude data collection, and in particular, to a constant magnification imaging system and method based on firmware up-sampling without specialized optics.
When an image is taken using a standard camera lens objects appear larger when they are closer to the camera than when they are further from the camera. This is due to optical perspective, which causes images of rectangular objects to appear trapezoidal when viewed with one edge of the rectangle closer to the camera than the opposite edge. An example, although not limited thereto, where such a problem is of particular significance is in applications in which parcels are aligned, traveling down a conveyor belt and imaged by a line scan camera, in which the top, bottom, left and right side images are rectangular. However, if an attempt is made to scan the leading or trailing surface of the box, the result is a trapezoidal image. This causes complications with contextual analysis software that is trying to determine if a particular block of text is a destination address, using relative position as one of the deciding factors. The problem is complicated further if the parcels are not aligned on the conveyor belt as they pass the scan line and four out of the six sides are in various degrees of distortion.
To simplify the contextual analysis algorithms required for this function, and thereby accelerate the overall assignment process, methods have been developed to produce “constant magnification” images. These techniques remove the optical perspective property and images of leading and trailing sides of a box appear as if they were perfectly aligned side surfaces, resulting in undistorted rectangular images. However, the current methods for producing constant magnification images are either large and unwieldy, such as telecentric optics, or are made up of high speed mechanisms, such as dynamic zoom/focus lens, that are prone to failure. These devices also add significant cost to the camera system.